Aims: 

Aldosterone is the last component of the renin-angiotensin-aldosterone system inducing its peripheral effects via mineralocorticoid receptors (MR). Brain MR are mainly occupied by glucocorticoids. Recent studies indicate that manipulations with MR in the brain are associated with behavioural changes. We have investigated anxiety-like behaviour and levels of selected hormones in response to chronic aldosterone treatment.

Methods: 

Rats were implanted subcutaneously with osmotic minipumps and treated with aldosterone or vehicle for two weeks. Elevated plus-maze test was used to measure anxiety-like behaviour and simultaneously, as a mild stressor to evaluate hormone responses.

Results: 

As measured by daily water intake, aldosterone treatment was found to increase water consumption (p < 0.05). Aldosterone-treated animals entered significantly less often (p < 0.05) and spent less time (p < 0.05) in the open arms of the elevated plus-maze. General locomotor activity was unchanged. Aldosterone treatment affected significantly also risk assessment behaviour. Basal plasma corticosterone and adrenocorticotropic hormone levels as well as their responses during stress remained unchanged after aldosterone treatment. Conclusions:

The present findings indicate an anxiogenic profile of aldosterone as demonstrated by alterations in several indicators of anxiety-like behaviour measured in the elevated plus-maze test. Chronic treatment with aldosterone failed to modify basal or stress-induced activity of the hypothalamic-pituitary-adrenocortical axis. Presented data suggest that the mechanisms of behavioural effects induced by aldosterone might be, at least partly, mediated via its effects on central mineralocorticoid receptors or by its non-genomic actions in the brain.

The study was supported by grants of APVV LPP – 0194-06 and VEGA 5064.